Takanelite is a rare manganese oxide mineral typically found in low-temperature hydrothermal deposits. It is often identified by its dull, earthy to submetallic black appearance and is found as thin crusts or powdery aggregates rather than well-defined crystals.
Is this takanelite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch takanelite with a known reference. Takanelite sits at Mohs 2.5-3, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: brownish black to dark brown.
- 3Read the lusterHold the specimen under a strong light. Luster: submetallic to dull.
- 4Match the color rangeCompare against the expected color range: black, brownish gray, steel gray.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: inclusions, massive.
Often confused with
Takanelite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Takanelite is noticeably harder (Mohs 2.5-3 vs. 1.5); streak differs, so Takanelite leaves brownish black to dark brown, Birnessite leaves brownish-black; luster reads submetallic to dull on Takanelite and dull on Birnessite.
How to tell apart: Psilomelane is the harder of the two (Mohs 5-6 vs. 2.5-3).
How to tell apart: Streak differs, so Takanelite leaves brownish black to dark brown, Pyrolusite leaves black, bluish black; luster reads submetallic to dull on Takanelite and metallic on Pyrolusite.
Often found alongside takanelite
Minerals reported to co-occur with takanelite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (Mn,Ca)₂xMn₁-xO₂·0.7H₂O
- Mohs hardness
- 2.5-3
- Density
- 3.43 g/cm³
- Streak
- Brownish black to dark brown
- Luster
- Submetallic to dull
- Transparency
- Opaque
- Crystal system
- Hexagonal
- Crystal habit
- Inclusions, massive
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Formed in the oxide zone of a bedded manganese deposit in metamorphosed cherts (Nomura mine, Japan); a secondary mineral derived from alteration of rhodochrosite in a manganese deposit (Janggun mine, South Korea)
Where rockhounds find takanelite
Classic worldwide localities
- Anson Betts mine, Plainfield, Hampshire Co., Massachusetts, and from Marfa, Presidio Co., Texas, USA
- Nomura mine, Ehime Prefecture, Japan
- Janggun mine, Bonghwa district, South Korea
Field-hunting tip
Where it forms: Formed in the oxide zone of a bedded manganese deposit in metamorphosed cherts (Nomura mine, Japan); a secondary mineral derived from alteration of rhodochrosite in a manganese deposit (Janggun mine, South Korea). If you start seeing braunite, todorokite, halloysite in float, you are in the right ground. Typical habit: inclusions, massive. Train your eye for that shape before scanning the outcrop.
Common questions
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Find takanelite on the map
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